Department of Molecular Genetics, University of Lodz, Lodz, Poland.
Mutat Res. 2011 Nov 1;716(1-2):51-8. doi: 10.1016/j.mrfmmm.2011.08.002. Epub 2011 Aug 19.
Tobacco smoking is one of the major risk factors in pathogenesis of head and neck squamous cell carcinomas (HNSCC). Many of the chemical compounds present in tobacco are well-known carcinogens which form adducts with DNA. Cells remove these adducts mainly by the nucleotide excision repair pathway (NER). NER also eliminates a broad spectrum of pyrimidine dimers (CPD) and photo-products (6-4PP) induced by UV-radiation or DNA cross-links after cisplatin anti-cancer treatment. In this study DNA damage and repair was examined in peripheral blood lymphocytes obtained from 20 HNSCC patients and 20 healthy controls as well as HTB-43 larynx and SSC-25 tongue cancer cell lines. DNA repair kinetics in the examined cells after cisplatin or UV-radiation treatment were investigated using alkaline comet assay during 240min of post-treatment incubation. MTT assay was used to analyse cell viability and the Annexin V-FITC kit specific for kinase-3 was employed to determine apoptosis after treating the cells with UV-radiation at dose range from 0.5 to 60J/m(2). NER capability was assessed in vitro with cell extracts by the use of a bacterial plasmid irradiated with UV-light as a substrate for the repair. The results show that lymphocytes from HNSCC patients and HTB-43 or SSC-25 cancer cells were more sensitive to genotoxic treatment with UV-radiation and displayed impaired DNA repair. Also evidenced was a higher rate of apoptosis induction after UV-radiation treatment of lymphocytes from the HNSCC patients and the HTB-43 cancer cells than after treatment of those from healthy donors. Finally, our results showed that there was a significant decrease in NER capacity in HTB-43 or SSC-25 cancer cells as well as in peripheral blood lymphocytes of HNSCC patients compared to controls. In conclusion, we suggest that the impaired NER pathway might be a critical factor in pathogenesis of head and neck cancer.
吸烟是头颈部鳞状细胞癌（HNSCC）发病机制中的主要危险因素之一。烟草中存在的许多化学物质是众所周知的致癌物质，它们与 DNA 形成加合物。细胞主要通过核苷酸切除修复途径（NER）去除这些加合物。NER 还消除了由 UV 辐射或顺铂抗癌治疗后 DNA 交联引起的嘧啶二聚体（CPD）和光产物（6-4PP）的广谱。在这项研究中，我们检查了 20 例 HNSCC 患者和 20 例健康对照者以及 HTB-43 喉和 SSC-25 舌癌细胞系外周血淋巴细胞中的 DNA 损伤和修复。使用碱性彗星试验在顺铂或 UV 辐射处理后 240 分钟的孵育期间，研究了处理后检查细胞中的 DNA 修复动力学。使用 MTT 测定法分析细胞活力，并用针对激酶-3 的 Annexin V-FITC 试剂盒在剂量范围为 0.5 至 60J/m（2）时用 UV 辐射处理细胞后确定细胞凋亡。在体外使用细菌质粒作为修复的底物，通过细胞提取物评估 NER 能力。结果表明，与健康供体相比，HNSCC 患者、HTB-43 或 SSC-25 癌细胞的淋巴细胞对 UV 辐射的遗传毒性处理更敏感，并且显示出受损的 DNA 修复。还证明了与健康供体相比，HNSCC 患者和 HTB-43 癌细胞的淋巴细胞在接受 UV 辐射处理后诱导细胞凋亡的速率更高。最后，我们的结果表明，与对照组相比，HTB-43 或 SSC-25 癌细胞以及 HNSCC 患者外周血淋巴细胞中的 NER 能力显著降低。总之，我们认为受损的 NER 途径可能是头颈部癌症发病机制中的关键因素。
